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BIG PHYSICS, BIG QUESTIONS –

Aspirin “reduces lung cancer risk”

By Gaia Vince

Regular use of aspirin more than halves the risk of lung cancer in women who smoke, according to research in New York. But other cancer experts warn the study group is small, and say smokers should give up – not take aspirin to reduce their lung cancer risk.

The 12-year study of 889 smoking and non-smoking women – 81 of whom developed lung cancer – found that those who took aspirin three times a week for six months or more were a third less likely to have developed lung cancer.

The drug was particularly effective in preventing non-small cell lung cancer – the most common type, which is associated with tobacco smoking. The women who smoked and took aspirin regularly had a 61 per cent lower chance of developing this form of lung cancer than women who smoked and did not take aspirin. Taking aspirin also slightly reduced the risk of small cell lung cancer – caused by radiation exposure during radiotherapy, for example.

“We believe aspirin has an anti-inflammatory effect on the component present in tobacco smoke that causes inflammation and lung cancer,” says Paolo Toniolo, at New York University School of Medicine, who carried out the study. He says it is not clear what that component is.

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“But the results are quite extraordinary and suggest that aspirin should be prescribed as a cancer prevention method for former smokers who retain chronic inflammation of the lungs for decades after stopping smoking,” he told New Scientist.

There are an estimated 71,200 new cases of non-small cell carcinoma in the UK and US alone each year.

“Looks convincing”

“Nobody knows for certain why, but a number of cancers – such as lung, colon, liver and uterine – are accompanied by chronic inflammation. Exposure to tobacco smoke over time produces mucus and a cough, which are signs of constant irritation of the tracheo-bronchal tree,” he told New Scientist.

“Aspirin may also have a further beneficial effect in that it speeds up apoptosis, cell death, which is significantly slowed among mutated cells that lose the ability to die,” he added.

However other cancer experts have greeted the results cautiously, pointing out that smoking causes nine out of 10 lung cancer deaths, and that giving up has the biggest effect on reducing risk. “Although the data looks convincing, it is just one small study and we would like to see much larger studies done,” says Leslie Walker at Cancer Research UK.

“But it is interesting, because the number of cancers where aspirin is linked to reducing risk is growing. And the evidence that the inflammatory process is involved is also mounting,” she adds.

A separate Europe-wide study of smoking trends has predicted that health campaigns will cause lung cancer deaths in the UK to fall over the next five years, by 20 per cent in men and eight per cent in women. But death rates in some European countries remain high, says Paul Brennan of the International Agency for Research on Cancer, who led the study.